The present invention relates to electric motor enclosures, and more particularly to an improved resilient gasket for sealing the opening through which the motor leads pass.
Depending upon their application electric motors require various degrees of enclosure, both to protect the internal portions of the motor from dirt build-up, corrosion, and damage but also to shield the surrounding environment from heat or electrical discharges which may occur within the motor. Types of motors in common use range from open-style motors through totally-enclosed, fan cooled (TEFC) motors to explosion-proof motors. Various techniques have been developed for sealing motor enclosures, depending upon the environment in which the motor is to operate, and to meet the requirements of industrial, government, and military standards. For many applications, it is necessary that the cables or leads which conduct current to the motor windings, and which necessarily pass through the motor enclosure, be sealed so as to prevent moisture, dirt and other foreign materials from entering the motor. At the same time, it is desirable that the lead-sealing means be easily removable in the event that the motor has to be repaired.
For typical industrial applications, from 3 to 9 leads extend from the motor enclosure, typically through a large, common opening. Depending upon the application and type of motor the opening may be closed by various means including gaskets, bulk sealing material, and/or a removable outside housing coupled to a conduit.
In some approaches a flat, resilient gasket is secured across an opening in the motor enclosure and holes or slits cut in the gasket to allow the leads to extend therethrough. This approach has the disadvantage of requiring specifically-sized apertures or the use of circular cutters for providing a round aperture which will seal evenly around each lead.
By simply cutting a slit in the material, a satisfactory seal may not be achieved. If the gaskets are pre-cut, they are obviously not usable with lead sizes which do not match the pre-cut holes. In an effort to obtain a better degree of sealing, lead openings are frequently sealed by filling them with a substance which will cure or set, and in that manner permanently seal the opening about the leads. This method has the disadvantage of being awkward and messy in a production line environment, and further requiring that the motor be held in a proper position until the sealing material hardens. Still further, when it is necessary to repair the motor or to replace the leads the sealing material must be destroyed, and cannot be re-used but instead the sealing or encapsulation step must be redone. Accordingly, it will be appreciated that it would be highly desirable to provide an improved lead seal gasket for an electric motor which overcomes the above-mentioned disadvantages.
It is therefore an object of the present invention to provide an improved lead seal gasket for an electric motor.
Another object is to provide a lead seal gasket which is adaptable for use with leads of various sizes.
Still another object is to provide a lead sealing means which can be reused, which yet provides a uniform, tight seal about each lead.